[ANGLÈS] In the last decade, the use of mobile phones in aircraft has become a reality. A growing number of flights have onboard GSM installations that enable this. However, such systems require some RF planning efforts to integrate them into the desired aircraft. In these preliminary stages, coverage studies are commonly undertaken. The present document species the design and implementation of a tool that aims to be useful for such studies. This tool, called ConneX Simulator, is able to simulate the above-mentioned GSM installations and to provide reliable and meaningful results for coverage. To the best of the author's knowledge, no tool with these same characteristics was available for this purpose in aircraft environments up until now. The first phase of this project was to specify the system requirements and the work plan. Then, the available technologies for both the design and the implementation were studied. The next steps aimed at its design and its implementation. The developed system is a RESTful web application composed of three parts: a processing unit (CORE), which carries out the coverage calculations; an application programming interface (API), as an abstraction layer between the processing unit and the graphical user interface; and the graphical user interface (GUI), which aids to ease the user interaction with the system. This document is structured as follows: In Chapter 1, an introduction is given describing the project background and its scope; in Chapter 2, the requisites that the system must satisfy are described, as well as the more general use cases; then, in Chapter 3, an overview of the system design and a description of its dependencies regarding to other systems are given. In Chapter 4, a more detailed design of the three main subsystems and their development is explained. In the next one, Chapter 5, there is a practical approach of the system in an specic scenario. Finally, there are some concluding remarks, Chapter 6, the project references and the appendices.